There are several prior art assemblies for locking bearings into a motor end frame, thus preventing axial movement of a motor shaft. Assemblies previously disclosed for this purpose include clamping a bearing to a housing with a metal plate and screws, using custom formed bolts, press fitting a bearing into a housing, and securing bearings with an adhesive.
As can be appreciated, electric motors of the type contemplated for use with the present invention generally need repairing from time to time. Typically, for example, bearings need replacing, shafts need reworking or replacing, and any number of internal electrical components may need fixing or replacing. When disassembling a motor for repair, it is sometimes necessary or desirable to remove a bearing from a motor end frame. The bearing lock devices of the prior art all present problems with efficiently removing a bearing from an end frame.
In addition to being able to efficiently repair a motor by disassembling a bearing from an end frame, ease of assembly is also of concern. The prior art bearing lock mechanisms present various problems in terms of assembly.
Using a metal plate to unlock a bearing from an end frame generally requires completely unscrewing the plate from the end frame. Since the metal plate is removed from the end frame, parts may be lost or misplaced, preventing efficient reassembly of the bearing onto the motor end frame. Affixing a metal plate to an end frame in order to lock a bearing in place requires that the bearing first be installed in the end frame and then the metal plate is positioned over the bearing. The plate and bearing must be held in place as screws fasten the plate to the end frame.
Using custom formed bolts generally requires the use of special tools in order to install and remove the bolts, such tools being known to those skilled in the art. If the appropriate tools are not readily available, installing or removing a bearing from an end frame may be delayed. Additionally, when using custom made bolts, the bolts must be specially made and the end frame must be properly formed to accommodate the custom bolts.
To remove a bearing that has been press fit into an end frame, either the bearing must be mechanically removed from the end frame, or the location where the bearing mates with the end frame must be heated or cooled, depending on the type of material used for the bearing and the end frame, in order to separate the bearing from the end frame. When press fitting a bearing into an end frame, special machinery and processes must be used, as known by those skilled in the art.
Removing a bearing that has been adhesively attached to an end frame generally destroys the adhesive. In order to return or replace the bearing, further adhesive must be appropriately applied. Securing a bearing with adhesive requires the use of a special adhesive capable of withstanding the environment of an electric motor, as known by those skilled in the art.
The prior art bearing lock devices and processes add unnecessary cost, complexity and time to the overall assembly of securing a bearing to an end frame.
Another prior art device which secures a bearing to an end bell of a motor is described in U.S. Pat. No. 2,772,929. In the '929 patent, dogs 62 engage stops 66 which are formed on the inner surfaces of a boss 52. Boss 52 must be properly aligned with the outer surface of bearing 22 in order for the dogs 62 to affix the bearing 22 in place. However, since stops 66 are formed on the boss 52, machining the boss to the proper dimension based on the width of the bearing is not possible. Thus, if boss 52 does not properly align with the outer surface of bearing 22 when bearing 22 is placed within boss 52, the boss cannot be easily machined to proper size. If the bearing 22 outside surface does not properly coincide with the top surface of boss 52, the bearing will not be properly fixed to the end bell, thereby possibly causing operational problems with the motor.